The present invention generally relates to magnetic recording and/or reproducing apparatuses, and more particularly to a magnetic recording and/or reproducing apparatus which has at least two modes with mutually different carrier frequencies and automatically carries out the recording and/or the reproduction in one of the two modes.
Presently, an existing video tape recorder (hereinafter simply referred to as a VTR) for home use employs a standard magnetic tape (hereinafter simply referred to as standard tape) with a tape width of 1/2 inch. This standard tape is an iron oxide magnetic tape having a coercivity Hc of approximately 600 Oe to 750 Oe and a residual flux density Br of approximately 1100 G to 1300 G, for example. The recording is carried out on the standard tape with the carrier frequency set between approximately 3.4 MHz and 5.5 MHz, and for example, the carrier frequency is set between 3.4 MHz and 4.4 MHz. However, due to the recent improvements in the performance of the magnetic tape and the magnetic head, there is a demand for a VTR which can record and reproduce a high quality picture having a higher resolution.
For this reason, a VTR has been proposed in which the recording is intended to be made on a high performance magnetic tape (hereinafter simply referred to as high performance tape) such as a metal magnetic tape (hereinafter simply referred to as a metal tape) with the carrier frequency of 5 MHz to 7 MHz, for example, which is adequately high for utilizing the high quality and resolution recording (hereinafter referred to as a high quality mode). One of such high performance tape is a type of metal magnetic tape already used in the so-called 8-mm VTRs and the VTRs for professional use, and has a coercivity Hc of approximately 1300 Oe to 1500 Oe and a residual flux density Br of approximately 2700 G to 2800 G.
Because of the fact that the higher carrier frequency and other recording and reproducing parameters, which are different from that of the standard mode, are needed for the high quality mode, the signals recorded on a tape in the high quality mode cannot be reproduced in the standard mode or vice versa. In other words, there is no electro-magnetic compatibility between the standard and high quality modes.
There is another problem of tape itself that if the high performance tape mentioned in the foregoing paragraph was attempted to be used with the existing VTR for home use and played in the standard mode, the desired performance would not be obtained because the recording current flowing to its magnetic head would be insufficient for the coercivity Hc of the high performance tape which is approximately 1300 Oe or over and is considerably high compared to that of the standard tape. Furthermore, a poor audio performance due to its long wavelength in the recording and reproduction and a poor erasing performance would result. For these reasons, this type of metal high performance tape is unsuited for the standard mode.
On the other hand, the standard tape is unsuited for the high quality mode because of the poor performance mainly due to its low coercivity compared to that of the high performance tape.
In this regard, it is conceivable to design a type of VTR having exclusively the high quality mode for using the high performance tape only, but this type of VTR naturally has no tape interchangeability with the existing VTR for home use. If utilized, it would be disadvantageous to the user in that he must have both the existing VTR for playing the standard tape in the standard mode and another type of VTR for playing the high performance tape in the high quality mode, and the high performance tape is unusable on the existing VTR.
Hence, it comes to develop a VTR having a switching means for switching the operation mode between the standard and high quality modes, and to develop a high performance tape accommodated within a tape cassette which has an external form and size identical to those of the existing tape cassette accommodating the standard tape and has magnetic characteristics acceptable for both the standard and the high quality modes, which makes the tape usable in both the modes. In this case, the user operates the switching means to select the appropriate one of the standard and high quality modes depending on which mode he wishes to use for recording or which mode of recorded tape cassette he is going to playback. But in this case, the user must visually identify the tape cassette which accommodates either the standard or the high performance tape every time a tape cassette is loaded into the VTR, and the user may make an error in identifying the tape cassette. As a result, the user may carry out a recording on the standard tape in the high quality mode, and in this case, no satisfactory reproduced picture is obtained at the time of the reproduction and the user may mistake that the VTR is malfunctioning. The user may make a similar error when carrying out the reproduction with a tape of the standard or the high performance tape in the wrong mode.
In addition, because the tape cassettes accommodating the standard tape and the high performance tape have identical external form and size, the owner of the existing VTR exclusively with the standard mode may erroneously purchase a tape cassette accommodating the high performance tape. In this case, the owner of the existing VTR can use mechanically the tape cassette on his VTR but, the quality and the cost of the tape cassette may be more than necessary for his purpose. Hence, it would be confusing to the user when such two types of cassettes having identical external form and size are put on the market.